Medical access devices, particularly infusion devices, over-the-needle catheters, other catheters and feeding tubes are important tools for administration of fluids to patients. After placement, in normal management of a catheter or other medical access device in a patient, it is often necessary to be able to add or withdraw fluids through the device. In many surgical procedures, it is routine to place an intravenous catheter so that if it is necessary to medicate a patient during a procedure, the catheter already is in place. In other types of procedures it is necessary to administer medicaments periodically through the device or to withdraw samples. In all of these applications, the presence of a valve mechanism on the device to facilitate the addition of the medicament and to close the device after the addition is desirable.
The need for valved closures on medical access devices has been addressed in several patents. U.S. Pat. No. 5,085,645 teaches an over-the-needle catheter having an integral valve in a passage in the catheter hub. The patent discloses a valved adapter that is an integral part of a catheter hub.
U.S. Pat. No. 5,251,873 teaches a medical coupling site that is adapted to be attached directly to a standard male luer lock fitting. The coupling site includes a valve element contained within a tubular retainer. The coupling site includes a slit rubber diaphragm valve that is deflected by introduction of a male luer fitting and closes by the removal of the male luer. According to international standards, there is an allowable range of 2.5 mm in engagement length of a luer fitting. This variation in engagement length occurs because of variation in the outside diameter of the male projection and the inside diameter of the female receptacle of the luer fittings. Thus, a "fat" male luer will result in a "short" engagement length and conversely. Valves of the type disclosed in U.S. Pat. No. 5,251,873 may not open fully with male luer fittings at the "short" end of the allowable dimension, and since they also depend on the diaphragm for sealing around the male luer tip, they may also leak when a male fitting is mounted or may not fully close once opened.
U.S. Pat. No. 5,108,380 discloses a valve device for a hub member of a catheter. The valve is actuated by the placement of a male luer fitting which displaces a piston biased by a coil spring to open the valve.
U.S. Pat. No. 5,269,771 discloses a needleless introducer with a hem, static valve. The valve mechanism includes a plunger biased by a coil spring which, upon actuation, spreads a pair of resilient valve elements. This design may not be fully opened by a male luer fitting at the "short" side of the dimension, and the sealing depends upon the resilient valve elements closing against themselves. Further, the valve disclosed in U.S. Pat. No. 5,269,771 is composed of several different materials and is complex to assemble.
Additionally, U.S. application Ser. No. 08/288,170 which is commonly assigned to the assignee of the present disclosure teaches a valved adapter for a medical access device that includes a pusher for opening the valve with a proximal surface forming a substantially continuous surface with the proximal surface of the adapter when the valve is closed,
Valves and adapters of the type described above fall into a medical device category often referred to as "PRN" from the Latin pro re nata, i.e., as the circumstances may require. A typical example of usage for this type of device might be on a catheter left in place for three days. During this three day usage duration, a bolus dosage of a medicament might be given every 4 hours using a protocol including at each dosage interval: a) flushing the catheter to check patency; b) administration of the medicament; and c) flushing the medicament from the catheter with heparin or saline. During this typical usage period, this protocol results in 54 operations of the valve, i.e., 6 times a day, 3 steps each time and 3 days. In between each dosage the valve must not leak, and it must be readily reopened. Previously, the bolus introduction may have been made using hypodermic needles penetrating a resilient septum. However, a septum may start leaking after multiple penetrations with a sharp needle. Because of this leakage potential and the concerns about risks to practitioners and service personnel from "sharps", hospitals have changed many protocols to reduce the use of pointed hypodermic needles. The PRN adapters as described above have been developed to address the hospitals' changing needs.
While the teachings cited above address many of the practitioners' concerns, there is still a need for a valved adapter for medical access devices that offers rapid, easy-to-use access with automatic positive on/off flow control. Devices such as disclosed above generally depend upon the placement of a male luer fitting of a fluid handling device onto a female luer fitting of the adapter to open the valve with the removal of the male luer fitting allowing the valve to close. Users of many of these devices have become aware that, since the valve in the adapter generally closes as the male luer fitting is removed, the closure of the valve often causes a small fluid discharge or "spurt" of fluid from the adapter. Because of the well documented concerns regarding fluid borne pathogens, such uncontrolled discharges are most undesirable.
Another problem noted in currently available adapters, that have a valve that closes as the male luer fitting is removed, is termed "backflow". As an example, a syringe with a male luer is used to deliver a fluid into an adapter mounted on a venous catheter. When the contents of the syringe are expelled, a continuous liquid column exists from the syringe to the open end of the catheter in the blood vessel. When the syringe is removed, the volume of the liquid column present in the syringe tip is removed from the column resulting in a like volume of blood being drawn back into the catheter. This "backflow" blood may clot and cause blockage in a subsequent use of the catheter.
Thus, while there are many forms of adapters available, there is still a need for an adapter which substantially prevents uncontrolled fluid discharges from adapters and backflow into catheters attached to adapters as fluid handling devices are dismounted. Additionally, some of the currently available adapters are open at the proximal end requiring an additional plug or cover to avoid contamination of the fitting when a fluid delivery device is not mounted. A device having these features plus the advantage of being self closing and easily cleanable is disclosed herein below.